Assessing Carburetor Icing Risk and Response

Assessing the Risk of Carburetor Icing Today The risk of carburetor icing is highest when temperatures range between -5°C and +15°C with a narrow temperature-dew point spread. By plotting the temperature and dew point on a graph, you can better understand which temperature ranges pose the greatest risk for carb ice formation. Before flying, check the temperature-dew point spread and apply carb heat regularly to mitigate the risk of icing.

Identifying and Responding to Carburetor Icing If carburetor icing occurs, you will notice your engine running roughly. First, ensure that you have an adequate fuel supply. If carb ice is suspected, activate the carb heat and keep it on. Initially, the engine may run even rougher as the ice melts and the engine attempts to burn off the resulting water. Do not turn off the carb heat during this phase.

Once the carb ice has melted and passed through the engine, power should return to nearly normal. Keep in mind that carb heat introduces warm, less dense air to the engine, which may cause a temporary drop in RPM. When you suspect the ice has been cleared, you can turn off the carb heat to restore normal engine power. Continue to monitor for potential icing by intermittently applying carb heat.

Case Study: Carburetor Icing Risk and Management

Case Study: Flight Incident Due to Carburetor Icing

Background: On a cold winter day, a pilot conducted a pre-flight check of a small single-engine aircraft. The outside temperature was +7°C, with a dew point of +1°C, creating a temperature-dew point spread of only 6°C. Based on the known risk factors for carburetor icing, this temperature range with a narrow dew point spread indicated a higher likelihood of carb ice formation.

Pre-Flight Assessment: The pilot, aware of the increased risk of carburetor icing, planned to monitor the situation closely. The pilot plotted the temperature and dew point on a graph and determined that the risk of carb icing was significant. To mitigate this risk, the pilot decided to apply carb heat regularly during the flight.

In-Flight Issue: After takeoff, the pilot noticed that the engine began running roughly. The pilot initially checked the fuel level to ensure it was sufficient and confirmed that fuel was not the issue. Suspecting carburetor icing, the pilot turned on the carb heat and kept it on, even though the engine’s roughness initially increased. This roughness was due to the melting ice causing the engine to burn off the water mixed with the fuel.

Troubleshooting and Response: The pilot followed the correct procedure by keeping the carb heat on despite the worsening engine performance. As the ice melted and was cleared from the carburetor, the engine’s performance began to improve. The pilot monitored the RPMs and, once they started stabilizing, turned off the carb heat to resume normal engine power. The pilot continued to intermittently apply carb heat to prevent re-icing as conditions changed.

Outcome: The pilot successfully managed the carburetor icing issue, and the engine performance returned to normal once the ice had cleared. By applying the carb heat regularly and monitoring the situation closely, the pilot ensured a safe flight despite the challenging conditions.

Lessons Learned:

1. Pre-Flight Preparation: Understanding the risk of carburetor icing based on temperature and dew point spreads is crucial. Properly plotting these values helps in anticipating potential issues.
2. Regular Monitoring: Continuously applying carb heat in conditions that are conducive to icing can prevent significant issues.
3. Responding to Engine Roughness: Immediate action, such as turning on the carb heat and monitoring the engine’s performance, is essential for managing carburetor icing effectively.

This case study illustrates the importance of proactive measures and correct response to carburetor icing, ensuring flight safety under challenging conditions.